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9

The rule of thumb a lot of people use is that lower frequencies will have better "penetration" than higher frequencies. That's true in some cases, but not all. This is probably derived from calculating skin depth of materials. The skin depth is just how deeply into a material an electromagnetic wave of a particular frequency can penetrate. The equation used ...


6

The dropout voltage is only "typically" 1.7V, there is no guarantee of how bad it can be other than that implied by the 40mA out at 5.3 in (so it's not a very good regulator for this application), but that does not explain why you're getting higher than 3.3V. Assuming it's the correct part number, and is not damaged, the simplest explanation is that \$V_{...


6

The basic mistake you are making is that you cannot use a voltage divider to power a circuit. Let's do the maths. For the sake of the maths I'll say the XBee needs 100mA to run. I don't know what the actual value is, but that seems a reasonable value to me for an RF transceiver. When unloaded you have a simple divider with current flowing through two ...


5

I think it's nothing to do with the MOSFET- the CR2477 simply has too much internal resistance to drive enough current to run your circuit. As the battery terminal voltage drops, your boost regulator will try to draw more and more current to keep the output voltage stable and at some point cannot work. According to the datasheet, the voltage is starting to ...


4

I had the same problem, it was caused by not waiting long enough after sending the message before re-asserting the sleep_rq pin. (@Dzarda got it). Experiment with different delays until it works. Edit: I know you have already set up SN and SP properly, but I'll leave this part of the answer in for others: The other thing to know is that you have to set SN ...


4

A WiFi network is designed to maintain a continuous connection. Thus all devices that are going to communicate must either burn a substantial amount of energy keeping the connection alive, or must spend a considerable length of time (typically 10-30 seconds) establishing a connection every time they want to communicate. When using xBee, if there's a "base ...


4

I know this is an old post, but since I stumbled on to it looking for a profile I had not seen before I figure this answer may help someone else. I've been working on this for a while - I don't consider my code "publishable" yet - I'm still using it in hack-and-sniff mode to find the clusters in question, but I can say the Light Link Application Profile is ...


4

You are using the old format for interrupts, I wonder if this is the cause of the problem. Please refer to avr/interrupt.h The interrupt handler should be like ISR(USART0_RX_vect) { }


4

I had a similar problem recently with an XBee device receiving an unexpected sequence of six characters while not receiving anything while in transparent mode. It's not too easy to track this down because the diagnostic "pitch mode" isn't mentioned in the datasheet but after discussions with Digi support once I was aware of the name I tracked down this ...


4

All the clues are in the answer linked to in your question. Here's a recap: - Using minimum data rate (20kbps) you need a theoretical power at the receiver of -111dBm Free space link loss at 10km is 120dB (use the formula - I've used 10km and 2.45GHz) If output power from transmitter is +10 dBm, receiver power is -110dBm That's almost a perfect match and ...


4

I think you'd be hard pressed to get the required 150mW or so, although it isn't impossible. Looking into piezo-based energy harvesting systems, one product claims about 7mW constant power. I would assume this scales reasonable well though. This is using a 3x7cm bendable piezo element and some electronics to store and convert the energy. There's a lot of ...


4

You could easily provide far more useful information than you have. If you are serious about getting good answers you can help yourself by giving as complete and accurate a description of the environment as possible subject to secrecy constraints. If secrecy is not an issue then tell us what you are doing. In the comments you say "5 to 10 meters" ...


4

A 3.3V regulator with a 1.7 dropout voltage should begin regulating at 5V. The datasheet shows that given an input of 8.3V, expected output voltage should be between 3.036 and 3.564V, with a typical of 3.3V. Your measurement of 4.765V is outside these specs, so either the regulator is defective, it's wired incorrectly, the measurement was not correct, or ...


4

Although the datasheet doesn't explicitly state a minimum load current, it does give the output regulation rating for 1 mA to 40 or 100 mA, implying to me that there is a minimum load required for the part to regulate (and I recall the older 78xx regulators specifiying a minimum 5 mA load current for proper operation). Put a 1 mA or more load on it and see ...


4

When you select resistors for use in a voltage divider there are a couple of things you need to take into account. In your case it is the output impedance of the sensor, roughly speaking how much current it can supply without messing up the output voltage, and the input impedance of the ADC. The input impedance of a ADC will be very high, usually it is the ...


4

Satellite is the solution. HF telemetry is incredibly specialised, requires licenses, and there are not "modules" in the sense you think of. (little pcbs that are cheap) There are many systems for data over HF radio, both commercial and amateur - go looking in the Ham radio world for Digital Modes where there is much info. Data rates are low. However, ...


3

You will need a micro controller of some sort to accomplish this task. (My favorite microcontroller when interfacing Arduino with XBee is the Arduino FIO or OSEPP Fio) You can accomplish this task one of two ways: Method 1, Read the XBee RSSI pin using Arduino pulseIn() On XBee and XBee-PRO modules, pin 6 is PWM0 / RSSI Output PWM Output 0 / RX Signal ...


3

Actually the answer from hanu is not correct. The XBee series 2 modules are ZigBee compliant (ZigBee Certification). What you called the "Digi stack" is only the application profile they use. ZigBee compliant means they use the official ZigBee stack but operate on a private application profile. If you configure your XBee Series 2 in API mode you can talk to ...


3

If there is a MAX232 on the XBee development kit, you need to add a level converter to the micro UART as well. If there is a way to bypass the MAX232 and connect to the XBee at the micro voltage levels, you could connect the micro Tx to the XBee Rx (and vice-versa) directly. If you don't want to wire up the MAX232 (and externals) yourself, you can use a ...


3

I had a similar question to this and never found anything simple and small enough for little AVRs etc. So I rolled something inspired by CAN. It's called MIN (Microcontroller Interconnect Network): https://github.com/min-protocol/min I've blogged about it here: https://kentindell.wordpress.com/2015/02/18/micrcontroller-interconnect-network-min-version-1-0/...


3

Pre-certification may apply to the module you are using, but you are still required for CE marking of the device. Part of the process for CE marking requires you to show evidence that your DEVICE conforms to the relevant harmonized requirements that covers emission and susceptibility. So you are still required to obtain CE marking to sell your product on ...


3

There is a lot of information that is lacking, so we'll have to make a few assumptions: That the room is not reflective to the frequencies that you're using, it would be best that it be absorptive. That system be as simple as possible Update is on the order of a few 10's of Hz. there is power limitations in the amount of energy you can broadcast. You ...


3

The correct answer is, of course, "with wires". I assume you've read the WiFi module's datasheet? A quick look at the XBee website shows that their WiFi module communicates over either UART or SPI. Implementing a UART or SPI master on an FPGA is (relatively) simple and, if you've never done much FPGA work before, a good learning experience. If you don't ...


3

The main consideration here is the frequency of operation - if the unused XBee and the one with the U.FL connection operate at the same frequency, you'll be fine. It won't make an appreciable difference whether you attach a U.FL antenna or if you solder the other wire antenna on. See here for a similar answer.


3

One of the disadvantage associated with zigbee modules for communication is the high cost. Moreover Zigbee is intended for short range. Radio links are the cheapest and long range solutions. NRF24L01 is one such radio link solution. NRF24L01 comprises 2Mbps RF transceiver IC for the 2.4GHz ISM (Industrial, Scientific and Medical) band. Extremely low power ...


3

This all depends on the frequency of current draw of the device on the line, the frequency response of the capacitors used, their ESR, parasitic inductance of traces joining capacitors and loads and actual physical layout. The purpose of decoupling capacitors is to provide a local power source for the load and keep the voltage rail clean (these two are ...


3

XCTU can't really do dynamic things like that. It's built almost exclusively to update firmware / check radio settings (and it's not even that good at that). You can send the same packet over and over every 10 seconds (Use the green + to make one, then send the sequence) However, as it turns out, your "programmed sequence" requires a program. A quick ...


3

Maybe I am late to answer this, but thought to share the ideas for others who may come across this question. You can use FTDI FT232RL or any such USB to TTL converter, connect Rx/Tx of one with Tx/Rx of other, pull down pin 3 (SPIMISO), then pull down Reset (Pin 22), then release reset and then release SPIMISO. This sequence would put JN516x in programming ...


3

Assuming the Adafruit Pro Trinket is just an ATMega328P running at 12 MHz, it cannot divide 12 MHz to an UART bit rate of 200 Kbps, while an ATMega328P running at 8 MHz can. So some clock speeds are just not compatible with some baud rates. A classic example is that an 8 MHz AVR can't use standard baud rate of 115200, but if you change the 8 MHz crystal to ...


2

A few problems: init_devices() must be called from inside main() otherwise it won't be run data = 0; and data = 1; do not send out the characters '0' and '1' respectively. They send out NUL and SOH: see http://www.asciitable.com, and these characters will show as nothing in a terminal emulator. Instead, enclose the values in quotes, e.g. data = '0';, to ...


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